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The First Gold-Catalyzed C[BOND]S Bond Formation: Cycloisomerization of α-Thioallenes to 2,5-Dihydrothiophenes


  • Financial Support by the Deutsche Forschungsgemeinschaft, the Fonds der Chemischen Industrie, and the European Community (COST D24/0003/01) is gratefully acknowledged.


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One good ring deserves another: A highly efficient and stereoselective cycloisomerization of α-thioallenes to 2,5-dihydrothiophenes is the first example of a gold-catalyzed carbon–sulfur bond formation (see scheme, X=Cl, I). Both gold(I) and gold(III) salts can be used as the precatalyst, with AuCl and AuI giving the best yields. The method is of interest for the stereoselective synthesis of biologically active 2,5-disubstituted dihydro- or tetrahydrothiophenes.